[sdiy] Many SPI slave devices on the same PIC master BUS..

Brian Willoughby brianw at audiobanshee.com
Tue Mar 2 02:31:34 CET 2021


I don't think there should be a strict limit. Any fan-out issues could be handled by buffer/drivers on MOSI and SCK, although MISO would be difficult unless the drivers were tri-stated by the same Chip Select used for each chip.

I seem to recall designing with as many as 3 SPI slave devices on a PIC, maybe even 5.

I think you'll want to 'scope all three bus signals to look at the edges, and to decide whether a boost from a driver is needed.

Which PIC part number are you using? The data sheet should have a chapter on the pin electronics specific to SPI.

Brian


On Mar 1, 2021, at 16:55, Jean-Pierre Desrochers wrote:
> Did anybody used in the past as much as 6 x SPI slaves devices
> driven by the same micro master bus (MISO, MOSI, SCK)?
> Obviously one at the time and each of them having their own separate Chip select pulse ? 
> I cannot see anywhere if there is a limit for SPI slaves sharing
> the same bus (loading, fan out..)





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